After reading the above linked instruction manual more carfully and until the end, I found the solution:
# Define a monitor
my_monitor = monitors.Monitor(name='my_monitor_name')
my_monitor.setSizePix((1280, 800))
my_monitor.setWidth(20)
my_monitor.setDistance(100)
my_monitor.saveMon()
After that, you will be able to load “my_monitor_name” when opening a visual.window